System and method for automatic routing of dynamic host configuration protocol (dhcp) traffic

ABSTRACT

At an intermediary dynamic host configuration protocol relay device, over a network, a dynamic host configuration protocol message is obtained from one of a plurality of remote dynamic host configuration protocol relay devices in communication with the intermediary dynamic host configuration protocol relay device over the network. The intermediary dynamic host configuration protocol relay device accesses data pertaining to a plurality of dynamic host configuration protocol back-end servers logically fronted by the intermediary dynamic host configuration protocol relay device. Based on information in the dynamic host configuration protocol message and the data pertaining to the plurality of dynamic host configuration protocol back-end servers, the dynamic host configuration protocol message is routed to an appropriate one of the plurality of back-end dynamic host configuration protocol servers.

FIELD OF THE INVENTION

The present invention relates generally to communications systems andmethods, and, more particularly, to the dynamic host configurationprotocol (DHCP) and the like.

BACKGROUND OF THE INVENTION

Until fairly recently, the cable network was predominantly a vehicle fordelivering entertainment. With the advent of the Internet and the risein demand for broadband two-way access, the cable industry began to seeknew ways of utilizing its existing plant. Pure coaxial (“coax”) cablenetworks were replaced with hybrid fiber networks (HFNs) using opticalfiber from the head end to the demarcation with the subscriber coax(usually at a fiber node). Currently, a content-based network, anon-limiting example of which is a cable television network, may affordaccess to a variety of services besides television, for example,broadband Internet access, telephone service, and the like.

One significant issue for a cable operator desiring to provide digitalservice is the configuration of its network. Designed for one-waydelivery of broadcast signals, the existing cable network topology wasoptimized for downstream (toward the subscriber) only service. Newequipment had to be added to the network to provide two-waycommunication. To reduce the cost of this equipment and to simplify theupgrade of the broadcast cable for two-way digital traffic, standardswere developed for a variety of new cable-based services. The first ofthese standards, the Data Over Cable System Interface Standard (DOCSIS®standard), was released in 1998. DOCSIS® establishes standards for cablemodems and supporting equipment. DOCSIS® (Data Over Cable ServiceInterface Specification) is a registered mark of Cable TelevisionLaboratories, Inc., 400 Centennial Parkway Louisville Colo. 80027, USA,and will be referred to for the remainder of this application in capitalletters, without the ® symbol, for convenience.

IP addresses are allocated in blocks known as subnets or prefixes on anetwork. These addresses are regularly allocated and moved as part ofnetwork growth and expansion. A cable modem termination system or CMTSis a piece of equipment typically located in a cable company's head endor hub site, and used to provide high speed data services, such as cableInternet or voice over Internet Protocol (VoIP), to cable subscribers. ACMTS provides many of the same functions provided by the digitalsubscriber line access multiplexer (DSLAM) in a digital subscriber line(DSL) system.

On a DOCSIS network, IP subnets are allocated on a per-CMTS basis.

The Dynamic Host Configuration Protocol (DHCP) is a network protocolthat is used to configure network devices so that they can communicateon an IP network. A DHCP client uses the DHCP protocol to acquireconfiguration information, such as an IP address, a default route andone or more DNS (domain name system) server addresses from a DHCPserver. The DHCP client then uses this information to configure itshost. Once the configuration process is complete, the host is able tocommunicate on the internet.

The DHCP server maintains a database of available IP addresses andconfiguration information. When it receives a request from a client, theDHCP server determines the network to which the DHCP client isconnected, and then allocates an IP address or prefix that isappropriate for the client, and sends configuration informationappropriate for that client.

Enterprise DHCP servers are commonly deployed in a cluster configurationwhere a pair of servers share responsibility for providing leases to adefined set of network infrastructure. In a cable network, a DHCPcluster is responsible for providing DHCP leases to clients configuredon a set of CMTSs. Each CMTS is configured with the IP addresses of thetwo DHCP servers and the servers are configured with the IP addressranges available on the CMTS. A DHCP cluster serves multiple CMTSs,typically grouped by geographic area.

There are many types of IP networks besides cable networks. Other wiredIP networks include, for example, digital subscriber line (DSL), fiberto the home, fiber to the curb, and so on. Wireless IP networks includeWi-Fi, wireless ISP (Internet Service Provider), WiMAX, satelliteinternet, and mobile broadband.

SUMMARY OF THE INVENTION

Principles of the present invention provide a system and method forautomatic routing of dynamic host configuration protocol (DHCP) traffic.In one aspect, an exemplary method includes the steps of obtaining, atan intermediary dynamic host configuration protocol relay device, over anetwork, a dynamic host configuration protocol message from one of aplurality of remote dynamic host configuration protocol relay devices incommunication with the intermediary dynamic host configuration protocolrelay device over the network; accessing, by the intermediary dynamichost configuration protocol relay device, data pertaining to a pluralityof dynamic host configuration protocol back-end servers logicallyfronted by the intermediary dynamic host configuration protocol relaydevice; and, based on information in the dynamic host configurationprotocol message and the data pertaining to the plurality of dynamichost configuration protocol back-end servers, routing the dynamic hostconfiguration protocol message to an appropriate one of the plurality ofback-end dynamic host configuration protocol servers.

In another aspect, an exemplary system includes an intermediary dynamichost configuration protocol relay device; a map database incommunication with the intermediary dynamic host configuration protocolrelay device; and a plurality of dynamic host configuration protocolback-end servers logically fronted by the intermediary dynamic hostconfiguration protocol relay device. The intermediary dynamic hostconfiguration protocol relay device is configured to obtain, over anetwork, a dynamic host configuration protocol message from one of aplurality of remote dynamic host configuration protocol relay devices incommunication with the intermediary dynamic host configuration protocolrelay device over the network; access the map database, the map databasecontaining data pertaining to the plurality of dynamic hostconfiguration protocol back-end servers logically fronted by theintermediary dynamic host configuration protocol relay device; and,based on information in the dynamic host configuration protocol messageand the data pertaining to the plurality of dynamic host configurationprotocol back-end servers, route the dynamic host configuration protocolmessage to an appropriate one of the plurality of back-end dynamic hostconfiguration protocol servers.

As used herein, “facilitating” an action includes performing the action,making the action easier, helping to carry the action out, or causingthe action to be performed. Thus, by way of example and not limitation,instructions executing on one processor might facilitate an actioncarried out by instructions executing on a remote processor, by sendingappropriate data or commands to cause or aid the action to be performed.For the avoidance of doubt, where an actor facilitates an action byother than performing the action, the action is nevertheless performedby some entity or combination of entities.

One or more embodiments of the invention or elements thereof can beimplemented in the form of an article of manufacture including a machinereadable medium that contains one or more programs which when executedimplement one or more method steps set forth herein; that is to say, acomputer program product including a tangible computer readablerecordable storage medium (or multiple such media) with computer usableprogram code for performing the method steps indicated. Furthermore, oneor more embodiments of the invention or elements thereof can beimplemented in the form of an apparatus (e.g., an intermediary dynamichost configuration protocol relay device) including a memory and atleast one processor that is coupled to the memory and operative toperform, or facilitate performance of, exemplary method steps. Yetfurther, in another aspect, one or more embodiments of the invention orelements thereof can be implemented in the form of means for carryingout one or more of the method steps described herein; the means caninclude (i) specialized hardware module(s), (ii) software module(s)stored in a tangible computer-readable recordable storage medium (ormultiple such media) and implemented on a hardware processor, or (iii) acombination of (i) and (ii); any of (i)-(iii) implement the specifictechniques set forth herein.

Techniques of the present invention can provide substantial beneficialtechnical effects. For example, one or more embodiments provide one ormore of:

-   -   simplification of CMTS configuration; only need to configure a        single pair of helper addresses;    -   in instances where distribution of load among back-end servers        is automated, eliminate need for manual intervention by an        operator;    -   ease in collecting metrics and/or statistics about DHCP traffic        in a network as same can be connected from one pair of servers        per data centers instead of from a large population of DHCP        servers; and    -   ability to re-write DHCP packets before seen by servers.

These and other features and advantages of the present invention willbecome apparent from the following detailed description of illustrativeembodiments thereof, which is to be read in connection with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an exemplary embodiment of a system, withinwhich one or more aspects of the invention can be implemented;

FIG. 2 is a functional block diagram illustrating an exemplary hybridfiber-coaxial (HFC) divisional network configuration, useful within thesystem of FIG. 1;

FIG. 3 is a functional block diagram illustrating one exemplary HFCcable network head-end configuration, useful within the system of FIG.1;

FIG. 4 is a functional block diagram illustrating one exemplary localservice node configuration useful within the system of FIG. 1;

FIG. 5 is a functional block diagram of a premises network, including anexemplary centralized customer premises equipment (CPE) unit,interfacing with a head end such as that of FIG. 3;

FIG. 6 is a functional block diagram of an exemplary centralized CPEunit, useful within the system of FIG. 1;

FIG. 7 is a block diagram of a prior art system;

FIG. 8 is a block diagram of a system automatic routing of DHCP traffic,in accordance with an aspect of the invention;

FIG. 9 is a block diagram of an exemplary DHCP relay, in accordance withan aspect of the invention;

FIG. 10 is a block diagram of a computer system useful in connectionwith one or more aspects of the invention; and

FIG. 11 shows an alternative embodiment in the context of a metropolitanWi-Fi network.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

As noted, IP-based data services may be provided over a variety ofnetworks. Purely by way of example and not limitation, embodiments willbe shown in the context of a cable multi-service operator (MSO)providing data services as well as entertainment services. FIG. 1 showsan exemplary system 1000, according to an aspect of the invention.System 1000 includes a regional data center (RDC) 1048, and one or moredivisions, represented by division head ends 150. RDC 1048 and head ends150 are interconnected by a network 1046; by way of example and notlimitation, a dense wavelength division multiplex (DWDM) network.Elements 1048, 150 on network 1046 may be operated, for example, by oron behalf of a cable MSO, and may be interconnected with a global systemof interconnected computer networks that use the standardized InternetProtocol Suite (TCP/IP) (transfer control protocol/Internet protocol),commonly called the Internet 1003; for example, via router 1008,National Data Center(1) 1049(1), discussed further below, and backbone1002. In one or more non-limiting exemplary embodiments, router 1008 isa point-of-presence (“POP”) router; for example, of the kind availablefrom Juniper Networks, Inc., Sunnyvale, Calif., USA.

Head ends 150 may each include a head end router (HER) 1091 whichinterfaces with network 1046. Head end routers 1091 are omitted fromFIGS. 2-5 below to avoid clutter.

RDC 1048 may include one or more provisioning servers (PS) 1050, one ormore Video Servers (VS) 1052, one or more content servers (CS) 1054, andone or more e-mail servers (ES) 1056. The same may be interconnected toone or more RDC routers (RR) 1060 by one or more multi-layer switches(MLS) 1058. RDC routers 1060 interconnect with network 1046.

FIG. 2 is a functional block diagram illustrating an exemplarycontent-based (e.g., hybrid fiber-coaxial (HFC)) divisional networkconfiguration, useful within the system of FIG. 1. See, for example, USPatent Publication 2006/0130107 of Gonder et al., entitled “Method andapparatus for high bandwidth data transmission in content-basednetworks,” the complete disclosure of which is expressly incorporated byreference herein in its entirety for all purposes. The variouscomponents of the network 100 include (i) one or more data andapplication origination points 102; (ii) one or more applicationdistribution servers 104; (iii) one or more video-on-demand (VOD)servers 105, and (v) consumer premises equipment or customer premisesequipment (CPE) 106. The distribution server(s) 104, VOD servers 105 andCPE(s) 106 are connected via a bearer (e.g., HFC) network 101. Servers104, 105 can be located in head end 150. A simple architecture is shownin FIG. 2 for illustrative brevity, although it will be recognized thatcomparable architectures with multiple origination points, distributionservers, VOD servers, and/or CPE devices (as well as different networktopologies) may be utilized consistent with embodiments of theinvention. For example, the head-end architecture of FIG. 3 (describedin greater detail below) may be used.

The data/application origination point 102 comprises any medium thatallows data and/or applications (such as a VOD-based or “Watch TV”application) to be transferred to a distribution server 104, forexample, over network 1102. This can include for example a third partydata source, application vendor website, compact disk read-only memory(CD-ROM), external network interface, mass storage device (e.g.,Redundant Arrays of Inexpensive Disks (RAID) system), etc. Suchtransference may be automatic, initiated upon the occurrence of one ormore specified events (such as the receipt of a request packet oracknowledgement (ACK)), performed manually, or accomplished in anynumber of other modes readily recognized by those of ordinary skill,given the teachings herein. For example, in one or more embodiments,network 1102 may correspond to network 1046 of FIG. 1, and the data andapplication origination point may be, for example, within RDC 1048 or onthe Internet 1003. Head end 150, HFC network 101, and CPEs 106 thusrepresent the divisions which were represented by division head ends 150in FIG. 1.

The application distribution server 104 comprises a computer systemwhere such applications can enter the network system. Distributionservers per se are well known in the networking arts, and accordinglynot described further herein.

The VOD server 105 comprises a computer system where on-demand contentcan be received from one or more of the aforementioned data sources 102and enter the network system. These servers may generate the contentlocally, or alternatively act as a gateway or intermediary from adistant source.

The CPE 106 includes any equipment in the “customers' premises” (orother appropriate locations) that can be accessed by a distributionserver 104 or a cable modem termination system 156 (discussed below withregard to FIG. 3). Non-limiting examples of CPE are set-top boxes andhigh-speed cable modems for providing high bandwidth Internet access inpremises such as homes and businesses.

Also included (for example, in head end 150) is a dynamic bandwidthallocation device (DBWAD) 1001 such as a global session resourcemanager, which is itself a non-limiting example of a session resourcemanager.

FIG. 3 is a functional block diagram illustrating one exemplary HFCcable network head-end configuration, useful within the system ofFIG. 1. As shown in FIG. 3, the head-end architecture 150 comprisestypical head-end components and services including billing module 152,subscriber management system (SMS) and CPE configuration managementmodule 3308, cable-modem termination system (CMTS) and out-of-band (OOB)system 156, as well as LAN(s) 158, 160 placing the various components indata communication with one another. In one or more embodiments, thereare multiple CMTSs 156-1 through 156-n. Each may be coupled to an HER1091, for example. See, e.g., FIGS. 1 and 2 of co-assigned U.S. Pat. No.7,792,963 of inventors Gould and Danforth, entitled METHOD TO BLOCKUNAUTHORIZED NETWORK TRAFFIC IN A CABLE DATA NETWORK, the completedisclosure of which is expressly incorporated herein by reference in itsentirety for all purposes.

It will be appreciated that while a bar or bus LAN topology isillustrated, any number of other arrangements (e.g., ring, star, etc.)may be used consistent with the invention. It will also be appreciatedthat the head-end configuration depicted in FIG. 3 is high-level,conceptual architecture and that each multi-service operator (MSO) mayhave multiple head-ends deployed using custom architectures.

The architecture 150 of FIG. 3 further includes amultiplexer/encrypter/modulator (MEM) 162 coupled to the HFC network 101adapted to “condition” content for transmission over the network. Thedistribution servers 104 are coupled to the LAN 160, which providesaccess to the MEM 162 and network 101 via one or more file servers 170.The VOD servers 105 are coupled to the LAN 158, although otherarchitectures may be employed (such as for example where the VOD serversare associated with a core switching device such as an 802.3z GigabitEthernet device; or the VOD servers could be coupled to LAN 160). Sinceinformation is typically carried across multiple channels, the head-endshould be adapted to acquire the information for the carried channelsfrom various sources. Typically, the channels being delivered from thehead-end 150 to the CPE 106 (“downstream”) are multiplexed together inthe head-end and sent to neighborhood hubs (refer to description of FIG.4) via a variety of interposed network components.

Content (e.g., audio, video, etc.) is provided in each downstream(in-band) channel associated with the relevant service group. (Note thatin the context of data communications, internet data is passed bothdownstream and upstream.) To communicate with the head-end orintermediary node (e.g., hub server), the CPE 106 may use theout-of-band (OOB) or DOCSIS® (Data Over Cable Service InterfaceSpecification) channels (registered mark of Cable TelevisionLaboratories, Inc., 400 Centennial Parkway Louisville Colo. 80027, USA)and associated protocols (e.g., DOCSIS 1.x, 2.0. or 3.0). The OpenCable™Application Platform (OCAP) 1.0, 2.0, 3.0 (and subsequent) specification(Cable Television laboratories Inc.) provides for exemplary networkingprotocols both downstream and upstream, although the invention is in noway limited to these approaches. All versions of the DOCSIS and OCAPspecifications are expressly incorporated herein by reference in theirentireties for all purposes.

Furthermore in this regard, DOCSIS is an internationaltelecommunications standard that permits the addition of high-speed datatransfer to an existing cable TV (CATV) system. It is employed by manycable television operators to provide Internet access (cable Internet)over their existing hybrid fiber-coaxial (HFC) infrastructure. Use ofDOCSIS to transmit data on an HFC system is one non-limiting exemplaryapplication of one or more embodiments. However, one or more embodimentsare generally applicable to IP transport of data, regardless of whatkind of network is employed.

It will also be recognized that multiple servers (broadcast, VOD, orotherwise) can be used, and disposed at two or more different locationsif desired, such as being part of different server “farms”. Thesemultiple servers can be used to feed one service group, or alternativelydifferent service groups. In a simple architecture, a single server isused to feed one or more service groups. In another variant, multipleservers located at the same location are used to feed one or moreservice groups. In yet another variant, multiple servers disposed atdifferent location are used to feed one or more service groups.

In some instances, material may also be obtained from a satellite feed1108; such material is demodulated and decrypted in block 1106 and fedto block 162. Conditional access system 157 may be provided for accesscontrol purposes. Network management system 1110 may provide appropriatemanagement functions. Note also that signals from MEM 162 and upstreamsignals from network 101 that have been demodulated and split in block1112 are fed to CMTS and OOB system 156.

Also included in FIG. 3 are a global session resource manager (GSRM)3302, a Mystro Application Server 104A, and a business management system154, all of which are coupled to LAN 158. GSRM 3302 is one specific formof a DBWAD 1001 and is a non-limiting example of a session resourcemanager.

An ISP DNS server could be located in the head-end as shown at 3303, butit can also be located in a variety of other places. One or more DHCPserver(s) 3304, 3305, 3306, discussed further below, could also belocated where shown or in different locations.

As shown in FIG. 4, the network 101 of FIGS. 2 and 3 comprises afiber/coax arrangement wherein the output of the MEM 162 of FIG. 3 istransferred to the optical domain (such as via an optical transceiver177 at the head-end 150 or further downstream). The optical domainsignals are then distributed over a fiber network to a fiber node 178,which further distributes the signals over a distribution network 180(typically coax) to a plurality of local servicing nodes 182. Thisprovides an effective 1-to-N expansion of the network at the localservice end. Each node 182 services a number of CPEs 106. Furtherreference may be had to US Patent Publication 2007/0217436 of Markley etal., entitled “Methods and apparatus for centralized content and datadelivery,” the complete disclosure of which is expressly incorporatedherein by reference in its entirety for all purposes. In one or moreembodiments, the CPE 106 includes a cable modem, such as aDOCSIS-compliant cable modem (DCCM).

Certain additional aspects of video or other content delivery will nowbe discussed for completeness, it being understood that embodiments ofthe invention have broad applicability to IP data communications andtransport. Again, delivery of data over a video (or other) contentnetwork is but one non-limiting example of a context where one or moreembodiments could be implemented. US Patent Publication 2003-0056217 ofPaul D. Brooks, entitled “Technique for Effectively Providing ProgramMaterial in a Cable Television System,” the complete disclosure of whichis expressly incorporated herein by reference for all purposes,describes one exemplary broadcast switched digital architecture,although it will be recognized by those of ordinary skill that otherapproaches and architectures may be substituted. In a cable televisionsystem in accordance with the Brooks invention, program materials aremade available to subscribers in a neighborhood on an as needed basis.Specifically, when a subscriber at a set-top terminal selects a programchannel to watch, the selection request is transmitted to a head end ofthe system. In response to such a request, a controller in the head enddetermines whether the material of the selected program channel has beenmade available to the neighborhood. If it has been made available, thecontroller identifies to the set-top terminal the carrier which iscarrying the requested program material, and to which the set-topterminal tunes to obtain the requested program material. Otherwise, thecontroller assigns an unused carrier to carry the requested programmaterial, and informs the set-top terminal of the identity of the newlyassigned carrier. The controller also retires those carriers assignedfor the program channels which are no longer watched by the subscribersin the neighborhood. Note that reference is made herein, for brevity, tofeatures of the “Brooks invention”—it should be understood that noinference should be drawn that such features are necessarily present inall claimed embodiments of Brooks. The Brooks invention is directed to atechnique for utilizing limited network bandwidth to distribute programmaterials to subscribers in a community access television (CATV) system.In accordance with the Brooks invention, the CATV system makes availableto subscribers selected program channels, as opposed to all of theprogram channels furnished by the system as in prior art. In the BrooksCATV system, the program channels are provided on an as needed basis,and are selected to serve the subscribers in the same neighborhoodrequesting those channels.

US Patent Publication 2010-0313236 of Albert Straub, entitled“TECHNIQUES FOR UPGRADING SOFTWARE IN A VIDEO CONTENT NETWORK,” thecomplete disclosure of which is expressly incorporated herein byreference for all purposes, provides additional details on theaforementioned dynamic bandwidth allocation device 1001.

US Patent Publication 2009-0248794 of William L. Helms, entitled “SYSTEMAND METHOD FOR CONTENT SHARING,” the complete disclosure of which isexpressly incorporated herein by reference for all purposes, providesadditional details on CPE in the form of a converged premises gatewaydevice. Related aspects are also disclosed in US Patent Publication2007-0217436 of Markley et al, entitled “METHODS AND APPARATUS FORCENTRALIZED CONTENT AND DATA DELIVERY,” the complete disclosure of whichis expressly incorporated herein by reference for all purposes.

Reference should now be had to FIG. 5, which presents a block diagram ofa premises network interfacing with a head end of an MSO or the like,providing Internet access. An exemplary advanced wireless gatewaycomprising CPE 106 is depicted as well. It is to be emphasized that thespecific form of CPE 106 shown in FIGS. 5 and 6 is exemplary andnon-limiting, and shows a number of optional features. Many other typesof CPE can be employed in one or more embodiments; for example, anydevice 813, 815, 817, 819 as described below, such as a cable modem, DSLmodem, and the like. Refer also to the discussion of a metropolitanWi-Fi embodiment below.

CPE 106 includes an advanced wireless gateway which connects to a headend 150 or other hub of a network, such as a video content network of anMSO or the like. The head end is coupled also to an internet (e.g., theInternet) 208 which is located external to the head end 150, such as viaan Internet (IP) backbone or gateway (not shown).

The head end is in the illustrated embodiment coupled to multiplehouseholds or other premises, including the exemplary illustratedhousehold 240. In particular, the head end (for example, a cable modemtermination system 156 thereof) is coupled via the aforementioned HFCnetwork and local coaxial cable or fiber drop to the premises, includingthe consumer premises equipment (CPE) 106. The exemplary CPE 106 is insignal communication with any number of different devices including,e.g., a wired telephony unit 222, a Wi-Fi or other wireless-enabledphone 224, a Wi-Fi or other wireless-enabled laptop 226, a sessioninitiation protocol (SIP) phone, an H.323 terminal or gateway, etc.Additionally, the CPE 106 is also coupled to a digital video recorder(DVR) 228 (e.g., over coax), in turn coupled to television 234 via awired or wireless interface (e.g., cabling, PAN or 802.15 UWB micro-net,etc.). CPE 106 is also in communication with a network (here, anEthernet network compliant with IEEE Std. 802.3, although any number ofother network protocols and topologies could be used) on which is apersonal computer (PC) 232.

Other non-limiting exemplary devices that CPE 106 may communicate withinclude a printer 294; for example over a universal plug and play (UPnP)interface, and/or a game console 292; for example, over a multimediaover coax alliance (MoCA) interface.

In some instances, CPE 106 is also in signal communication with one ormore roaming devices, generally represented by block 290.

A “home LAN” (HLAN) is created in the exemplary embodiment, which mayinclude for example the network formed over the installed coaxialcabling in the premises, the Wi-Fi network, and so forth.

During operation, the CPE 106 exchanges signals with the head end overthe interposed coax (and/or other, e.g., fiber) bearer medium. Thesignals include e.g., Internet traffic (IPv4 or IPv6), digitalprogramming and other digital signaling or content such as digital(packet-based; e.g., VoIP) telephone service. The CPE 106 then exchangesthis digital information after demodulation and any decryption (and anydemultiplexing) to the particular system(s) to which it is directed oraddressed. For example, in one embodiment, a MAC address or IP addresscan be used as the basis of directing traffic within the client-sideenvironment 240.

Any number of different data flows may occur within the network depictedin FIG. 5. For example, the CPE 106 may exchange digital telephonesignals from the head end which are further exchanged with the telephoneunit 222, the Wi-Fi phone 224, or one or more roaming devices 290. Thedigital telephone signals may be IP-based such as Voice-over-IP (VoIP),or may utilize another protocol or transport mechanism. The well knownsession initiation protocol (SIP) may be used, for example, in thecontext of a “SIP phone” for making multi-media calls. The network mayalso interface with a cellular or other wireless system, such as forexample a 3G IMS (IP multimedia subsystem) system, in order to providemultimedia calls between a user or consumer in the household domain 240(e.g., using a SIP phone or H.323 terminal) and a mobile 3G telephone orpersonal media device (PMD) user via that user's radio access network(RAN).

The CPE 106 may also exchange Internet traffic (e.g., TCP/IP and otherpackets) with the head end 150 which is further exchanged with the Wi-Filaptop 226, the PC 232, one or more roaming devices 290, or otherdevice. CPE 106 may also receive digital programming that is forwardedto the DVR 228 or to the television 234. Programming requests and othercontrol information may be received by the CPE 106 and forwarded to thehead end as well for appropriate handling.

FIG. 6 is a block diagram of one exemplary embodiment of the CPE 106 ofFIG. 5. The exemplary CPE 106 includes an RF front end 301, Wi-Fiinterface 302, video interface 316, “Plug n′ Play” (PnP) interface 318(for example, a UPnP interface) and Ethernet interface 304, eachdirectly or indirectly coupled to a bus 312. In some cases, Wi-Fiinterface 302 comprises a single wireless access point (WAP) runningmultiple (“m”) service set identifiers (SSIDs). In some cases, multipleSSIDs, which could represent different applications, are served from acommon WAP. For example, SSID 1 is for the home user, while SSID 2 maybe for a managed security service, SSID 3 may be a managed homenetworking service, SSID 4 may be a hot spot, and so on. Each of theseis on a separate IP subnetwork for security, accounting, and policyreasons. The microprocessor 306, storage unit 308, plain old telephoneservice (POTS)/public switched telephone network (PSTN) interface 314,and memory unit 310 are also coupled to the exemplary bus 312, as is asuitable MoCA interface 391. The memory unit 310 typically comprises arandom access memory (RAM) and storage unit 308 typically comprises ahard disk drive, an optical drive (e.g., CD-ROM or DVD), NAND flashmemory, RAID (redundant array of inexpensive disks) configuration, orsome combination thereof.

The illustrated CPE 106 can assume literally any discrete form factor,including those adapted for desktop, floor-standing, or wall-mounteduse, or alternatively may be integrated in whole or part (e.g., on acommon functional basis) with other devices if desired.

Again, it is to be emphasized that every embodiment need not necessarilyhave all the elements shown in FIG. 6—as noted, the specific form of CPE106 shown in FIGS. 5 and 6 is exemplary and non-limiting, and shows anumber of optional features. Yet again, many other types of CPE can beemployed in one or more embodiments; for example, any device 813, 815,817, 819 as described below, such as a cable modem, DSL modem, and thelike—refer also to the discussion of a metropolitan Wi-Fi embodimentbelow.

It will be recognized that while a linear or centralized busarchitecture is shown as the basis of the exemplary embodiment of FIG.6, other bus architectures and topologies may be used. For example, adistributed or multi-stage bus architecture may be employed. Similarly,a “fabric” or other mechanism (e.g., crossbar switch, RAPIDIO interface,non-blocking matrix, TDMA or multiplexed system, etc.) may be used asthe basis of at least some of the internal bus communications within thedevice. Furthermore, many if not all of the foregoing functions may beintegrated into one or more integrated circuit (IC) devices in the formof an ASIC or “system-on-a-chip” (SoC). Myriad other architectures wellknown to those in the data processing and computer arts may accordinglybe employed.

Yet again, it will also be recognized that the CPE configuration shownis essentially for illustrative purposes, and various otherconfigurations of the CPE 106 are consistent with other embodiments ofthe invention. For example, the CPE 106 in FIG. 6 may not include all ofthe elements shown, and/or may include additional elements andinterfaces such as for example an interface for the HomePlug A/Vstandard which transmits digital data over power lines, a PAN (e.g.,802.15), Bluetooth, or other short-range wireless interface forlocalized data communication, etc.

A suitable number of standard 10/100/1000 Base T Ethernet ports for thepurpose of a Home LAN connection are provided in the exemplary device ofFIG. 6; however, it will be appreciated that other rates (e.g., GigabitEthernet or 10-Gig-E) and local networking protocols (e.g., MoCA, USB,etc.) may be used. These interfaces may be serviced via a WLANinterface, wired RJ-45 ports, or otherwise. The CPE 106 can also includea plurality of RJ-11 ports for telephony interface, as well as aplurality of USB (e.g., USB 2.0) ports, and IEEE-1394 (Firewire) ports.S-video and other signal interfaces may also be provided if desired.

During operation of the CPE 106, software located in the storage unit308 is run on the microprocessor 306 using the memory unit 310 (e.g., aprogram memory within or external to the microprocessor). The softwarecontrols the operation of the other components of the system, andprovides various other functions within the CPE. Other systemsoftware/firmware may also be externally reprogrammed, such as using adownload and reprogramming of the contents of the flash memory,replacement of files on the storage device or within other non-volatilestorage, etc. This allows for remote reprogramming or reconfiguration ofthe CPE 106 by the MSO or other network agent.

The RF front end 301 of the exemplary embodiment comprises a cable modemof the type known in the art. In some cases, the CPE just includes thecable modem and omits the optional features. Content or data normallystreamed over the cable modem can be received and distributed by the CPE106, such as for example packetized video (e.g., IPTV). The digital dataexchanged using RF front end 301 includes IP or other packetizedprotocol traffic that provides access to internet service. As is wellknown in cable modem technology, such data may be streamed over one ormore dedicated QAMs resident on the HFC bearer medium, or evenmultiplexed or otherwise combined with QAMs allocated for contentdelivery, etc. The packetized (e.g., IP) traffic received by the CPE 106may then be exchanged with other digital systems in the localenvironment 240 (or outside this environment by way of a gateway orportal) via, e.g. the Wi-Fi interface 302, Ethernet interface 304 orplug-and-play (PnP) interface 318.

Additionally, the RF front end 301 modulates, encrypts/multiplexes asrequired, and transmits digital information for receipt by upstreamentities such as the CMTS or a network server. Digital data transmittedvia the RF front end 301 may include, for example, MPEG-2 encodedprogramming data that is forwarded to a television monitor via the videointerface 316. Programming data may also be stored on the CPE storageunit 308 for later distribution by way of the video interface 316, orusing the Wi-Fi interface 302, Ethernet interface 304, Firewire (IEEEStd 1394), USB/USB2, or any number of other such options.

Other devices such as portable music players (e.g., MP3 audio players)may be coupled to the CPE 106 via any number of different interfaces,and music and other media files downloaded for portable use and viewing.

In some instances, the CPE 106 includes a DOCSIS cable modem fordelivery of traditional broadband Internet services. This connection canbe shared by all Internet devices in the premises 240; e.g. Internetprotocol television (IPTV) devices, PCs, laptops, etc., as well as byroaming devices 290. In addition, the CPE 106 can be remotely managed(such as from the head end 150, or another remote network agent) tosupport appropriate IP services.

In some instances the CPE 106 also creates a home Local Area Network(LAN) utilizing the existing coaxial cable in the home. For example, anEthernet-over-coax based technology allows services to be delivered toother devices in the home utilizing a frequency outside (e.g., above)the traditional cable service delivery frequencies. For example,frequencies on the order of 1150 MHz could be used to deliver data andapplications to other devices in the home such as PCs, PMDs, mediaextenders and set-top boxes. The coaxial network is merely the bearer;devices on the network utilize Ethernet or other comparable networkingprotocols over this bearer.

The exemplary CPE 106 shown in FIGS. 5 and 6 acts as a Wi-Fi accesspoint (AP), thereby allowing Wi-Fi enabled devices to connect to thehome network and access Internet, media, and other resources on thenetwork. This functionality can be omitted in one or more embodiments.

In one embodiment, Wi-Fi interface 302 comprises a single wirelessaccess point (WAP) running multiple (“m”) service set identifiers(SSIDs). One or more SSIDs can be set aside for the home network whileone or more SSIDs can be set aside for roaming devices 290.

A premises gateway software management package (application) is alsoprovided to control, configure, monitor and provision the CPE 106 fromthe cable head-end 150 or other remote network node via the cable modem(DOCSIS) interface. This control allows a remote user to configure andmonitor the CPE 106 and home network.

The MoCA interface 391 can be configured, for example, in accordancewith the MoCA 1.0, 1.1, or 2.0 specifications.

As discussed above, the optional Wi-Fi wireless interface 302 is, insome instances, also configured to provide a plurality of unique serviceset identifiers (SSIDs) simultaneously. These SSIDs are configurable(locally or remotely), such as via a web page.

In addition to “broadcast” content (e.g., video programming), thesystems of FIGS. 1-6 also deliver Internet data services using theInternet protocol (IP), although other protocols and transportmechanisms of the type well known in the digital communication art maybe substituted. The IP packets are typically transmitted on RF channelsthat are different that the RF channels used for the broadcast video andaudio programming, although this is not a requirement. The CPE 106 areeach configured to monitor the particular assigned RF channel (such asvia a port or socket ID/address, or other such mechanism) for IP packetsintended for the subscriber premises/address that they serve.

As noted, enterprise DHCP servers are commonly deployed in a clusterconfiguration where a pair of servers share responsibility for providingleases to a defined set of network infrastructure. In a cable network, aDHCP cluster is responsible for providing DHCP leases to clientsconfigured on a set of CMTSs. Each CMTS is configured with the IPaddresses of the two DHCP servers and the servers are configured withthe IP address ranges available on the CMTS. A DHCP cluster servesmultiple CMTSs, typically grouped by geographic area.

Some embodiments are useful in novel DHCP infrastructures where DHCPservers are moved to national data centers (NDCs). As seen in FIG. 1,DHCP servers can, in general, be located in many different places. Somecurrent approaches locate the DHCP server(s) in a regional data center,as seen at 3304. On the other hand, some novel DHCP infrastructures, asjust noted, move the DHCP server(s) to one or more national datacenters. The non-limiting example of FIG. 1 shows a first NDC, nationaldata center (1), designated as 1049(1), and a second NDC, national datacenter (2), designated as 1049(2). The NDCs 1049(1) and 1049(2) may, forexample, be in geographically diverse locations such as, e.g., Coloradoand North Carolina. In such a case, one DHCP server from each pair islocated in Colorado and the other will be located in North Carolina. Ofcourse, some embodiments may utilize only a single NDC, or more than twoNDCs, or may involve clusters of DHCP servers that are not associatedwith NDCs and/or MSOs.

Note that the NDCs 1049(1) and 1049(2) may be connected by a suitableenterprise backbone network 1002 such as, by way of example and notlimitation, a private, high-bandwidth, Internet Protocol fiber opticnetwork.

One or more embodiments are useful in a wide variety of contexts. Someembodiments are particularly useful when transitioning the location ofDHCP servers from within one or more RDCs, as at 3304, to within one ormore NDCs, as at 3305, 3306. One manner to facilitate such a transitioninvolves a network operations team manually reconfiguring every CMTS (amodern MSO might have, for example, on the order of two thousand CMTSs)to point to the new DHCP server IP addresses as the DHCP servers move into the NDCs. In such a case, the reconfiguration of the CMTS musttypically be performed at the same time as the DHCP server work, inorder to avoid a DHCP outage for subscribers. In some such cases,further DHCP server work (such as server consolidation) will be carriedout after migrating to the national DHCP infrastructure, which willagain typically require updating the CMTS configuration simultaneouslywith any DHCP work.

Such a “brute force” approach, orchestrating CMTS configuration updatessimultaneously with back-end DHCP server work, potentially spanningdifferent operations teams, may be challenging. One or more embodimentsprovide a system and/or method useful in such a scenario, although itshould be noted that one or more embodiments are useful in manydifferent scenarios and are not limited to migration of DHCP serversfrom regional to national data centers.

Note that when a DHCP message is relayed by a network device, thenetwork device is referred to as a DHCP relay. In DHCP v.4, the clientsends a DISCOVER packet, the server sends an OFFER, the client thenresponds with a REQUEST, and the server responds with anACKnowledgement—DISCOVER, OFFER, REQUEST, AND ACK are thus examples ofDHCP messages. The DHCP relay inserts some of its own identifyinginformation in a DHCP request and forwards it on to its configured DHCPserver IP addresses. In a typical network design, the DHCP relayforwards the DHCP message directly to the DHCP server responsible forallocating leases on its behalf. One or more embodiments introduce anintermediary DHCP relay 843, discussed in detail in connection with FIG.8 below, between the DHCP relay (CMTS) and the DHCP server. This relaydetermines which back-end DHCP server is responsible for allocatingleases for the CMTS. The relay examines the DHCP request to determinewhich CMTS it originated from (based on the GIADDR (Gateway IP Address)field in the DHCP request). The relay takes the CMTS IP address andlooks it up against a map that provides a mapping of CMTS to back-endDHCP server IP address. After learning the back-end DHCP server IPaddress, the intermediary relay forwards the DHCP request to the correctback-end DHCP server.

With this approach, each CMTS in a network can be configured with acommon pair of DHCP server IP addresses. The IP addresses point to theintermediary DHCP relays for each of the two NDCs (primary andsecondary) (or to the corresponding load balancer(s) 909 if employed)which forward the DHCP request to the correct back-end serverautomatically. This allows a systems operations team or the like tocollapse or combine DHCP server clusters at will without requiringchanges on the CMTSs. It also simplifies the CMTS configuration becausethe DHCP server IP addresses are the same across the entire enterprise.The intermediary relay takes the responsibility of forwarding DHCPrequests to the correct back-end DHCP server, instead of the CMTS havingthis responsibility.

In some cases, the intermediary relay 843 automatically accesses theconfigurations of the DHCP servers it fronts so that it can build itsmap 849 (discussed below) automatically. By knowing how each DHCP serveris configured, the relay can build the CMTS-to-DHCP server mapprogrammatically, thus eliminating the need for a human to keep the mapup to date. Some embodiments collect the data approximately every minuteor so; thus, the map reflects changes made to a back-end DHCP server innear real-time.

One or more embodiments work equally well with DHCPv4 and DHCPv6. Theprotocol level changes necessary to forward the relayed messages differbetween DHCPv4 and DHCPv6; however, conceptually, the approach is thesame. When using DHCPv4, responses from the DHCP server bypass theintermediary relay and are sent directly to the CMTS. With DHCPv6,requests and responses are both routed through the intermediary relay.This is due to differences in the protocols.

Some embodiments have any one, some, or all of the following additionalfeatures:

-   -   The intermediary relay routes incoming DHCP requests based upon        additional criteria beyond the CMTS's IP address. Any        information contained in the DHCP request can be used to choose        an appropriate back-end server.    -   The intermediary relay modifies DHCP messages it is relaying, as        necessary, to affect the behavior of the DHCP server. This is        helpful in some cases; for example, where a CMTS sends some        incorrect information in its forwarded DHCP packets, which        causes current DHCP servers to reject packets that have been        relayed twice. Various example applications include VPN features        not supported by current CMTS software; it may be possible to        modify the DHCP messages in the intermediary relay so that the        DHCP server software “sees” all the information it expects when        processing the request.    -   Can easily be used for non-cable based networks. DHCP relaying        is an industry standard practice for access networks. Other        examples of situations where DHCP is commonly relayed include        Metro Wi-Fi, Mobile, and DSL networks. An exemplary relaying        approach according to one or more embodiments can benefit other        network operators outside the cable MSO domain by decoupling        configuration of the access device and DHCP server.    -   Some embodiments include a system (see discussion of work        assignment engine 854 elsewhere herein) that manages all the        back-end DHCP servers (e.g., 807, 809, 810) and moves CMTS        traffic among a set of servers based upon load. This system        spreads CMTS traffic across all the back-end servers and moves        and/or rebalances traffic dynamically without requiring changes        on the CMTS. This is different than the traditional load        balancing for the intermediate relay at 909, as discussed        elsewhere herein.

Thus, one or more embodiments may be useful in a variety of productsand/or services, such as, for example, DHCP relays and enterprise DHCPservers. Purely by way of example and not limitation, some embodimentsare helpful when changing the back-end DHCP server configuration for aCMTS infrastructure. By standardizing the CMTS configuration, a systemoperations team is empowered to perform back-end DHCP server workindependently without coordination with network operations or the like.

Advantageously, in one or more embodiments, the CMTS configuration willessentially never be wrong. In some current systems, a situation maydevelop where a CMTS has been configured with an incorrect DHCP serverIP address. If one of the two IP addresses is wrong, the CMTS will stillfunction because it is still “talking” to one server in the DHCPcluster. However, if the single working DHCP server becomes unreachable,the CMTS will be unable to communicate with the remaining (incorrectlyconfigured) server.

One or more embodiments thus employ a DHCP relay in front of a farm ofDHCP servers to distribute requests to the appropriate back-end server.In contrast, the current industry standard is a tight coupling (viaconfiguration) between the access device (CMTS, router, etc.) and theback-end DHCP server.

A more detailed discussion will now be provided with reference to FIGS.7-9. FIG. 7 shows a current system. There are a plurality of CMTSs 701,703 on the network. They perform a common DHCP function; they arefundamentally DHCP relay agents. DHCP is a protocol used on IP networkswhere client devices 713, 715, 717, 719 such as computers or cablemodems can use DHCP to obtain an IP address to use on the network thatthey are connected to. DHCP itself is a broadcast protocol. When acomputer is plugged into a network, it sends a broadcast message saying,in effect, “I need an IP address.” That broadcast message does not leavethe local network. The CMTS 701, 703 is responsible for listening forall the broadcast messages from IP devices 713, 715, 717, 719 connectedto the CMTS and relaying these messages to the appropriate DHCP server707, 709, 711; e.g., over backbone network 705. In one example of acurrent system, CMTSs 701, 703 are in one or more head ends 150;backbone 705 corresponds to network 1046, and DHCP servers 707, 709, 711are located in a regional data center as seen at 3304 in FIG. 1. Thedashed lines in FIG. 7 represent DHCP lease requests (and generally,DHCP messages) from CMTS_(A) 701 to DHCP₁ 707 and from CMTS_(B) to DHCP₂709.

The DHCP server is configured to match the configuration of the CMTS.The CMTS 701, 703 has a group of IP address blocks that it is configuredto use for clients 713, 715, 717, 719. The DHCP server 707, 709, 711 hasto have those same IP address blocks configured. The DHCP server 707,709, 711 is responsible for selecting an IP address for the client 713,715, 717, 719 which has sent that broadcast message which has in turnbeen relayed by the CMTS 701, 703. The DHCP server maintains all thestates. The DHCP server keeps track of how many addresses have beenallocated out of each block; it is responsible for finding an availableaddress and keeping track of how long addresses have been granted and/orleased for, and so on.

In the exemplary current system of FIG. 7, CMTS_(A), numbered 701, hasIP address 24.1.1.1 and is configured with the IP address of DHCP serverDHCP₁, numbered 707; namely 1.2.3.4. DHCP₁ is in turn configured tosupport CMTS_(A) with IP address 24.1.1.1. CMTS_(B), numbered 703, hasIP address 24.2.2.2 and is configured with the IP address of DHCP serverDHCP₂, numbered 709; namely 1.2.3.5. DHCP₂ is in turn configured tosupport CMTS_(B) with IP address 24.2.2.2. Any suitable number of DHCPservers may be included; in the non-limiting example of FIG. 7, DHCPserver DHCP₃, numbered 711, with IP address 1.2.3.6. Additional DHCPservers are suggested by an ellipsis.

When configuring a CMTS or other network device that is acting as a DHCPrelay agent, the IP address(es) of the DHCP servers that are configuredto support that network device must be provided. For example, on a CMTSfrom Cisco Systems, Inc. of San Jose, Calif., these are referred to asthe “DHCP helper IP addresses.” These addresses are configured on theCMTS and point to the DHCP servers that have been configured to supportthat CMTS. In the exemplary current system of FIG. 7, address 1.2.3.4 isconfigured on CMTSA and points to DHCP₁; while address 1.2.3.5 isconfigured on CMTSB and points to DHCP₂. Note that each CMTS 701, 703might be provided with a back-up address pointing to a secondary DHCPbut this is omitted from FIG. 7 to avoid clutter.

On an enterprise network with many CMTSs acting as relays, complicationensues. A modern network operated by an MSO may have about two thousandCMTSs and several hundred DHCP servers. When configuring CMTSs, it isnecessary to ensure that the DHCP server address matches the serverconfigured to support that CMTS. As noted above, some current systemsemploy a primary and secondary DHCP server configuration in aprimary-secondary relationship. If one IP address is correct on the CMTSbut the second is wrong, everything will operate normally until theprimary DHCP server fails; if the address does not point to the correctsecondary (backup) DHCP server, there will be an outage even though thebackup DHCP server is actually available.

As noted above, the configurational complexity of current systems hasled to operational challenges in keeping the addresses up to date. In acase where an MSO is centralizing its DHCP infrastructure, a “bruteforce” approach would likely result in having to change the helperaddresses on every CMTS 701, 703.

Turning now to FIG. 8, in an exemplary embodiment, DHCP relay 843 isinserted as shown. DHCP relay 843 “speaks” the DHCP protocol and isinserted between the CMTSs 801, 803 and all the back-end DHCP servers807, 809, 810. The responsibility of the relay 843 is to inspect theincoming DHCP lease requests or other DHCP messages that it receivesfrom the CMTSs 801, 803; determine what CMTS 801, 803 the requestoriginated from; and use a mapping database 849 to determine which DHCPserver 807, 809, 810 supports that CMTS. From the perspective of theCMTS, there will only be two helper addresses, namely, the relay 843 inthe primary data center (e.g., 1049(1)) and the relay in the backup datacenter (e.g., 1049(2)). The CMTSs will send traffic to the relays; therelays will look at the DHCP packet, note that it originated, forexample, from “CMTS_(A),” and know that CMTS_(A) is supported by DHCPserver DHCP₁. DHCP server DHCP₁ handles the message normally without anyspecial processing; it will merely have received the request and doesnot necessarily care that the relay 843 is in the middle of theconversation. DHCP server DHCP₁ simply handles the message normally andsends the response back to CMTS_(A).

In some cases, the map data database 849 is configured by an operator.However, in one or more embodiments, the configuration data is extractedout of all the DHCP servers 807, 809, 810 (i.e., which DHCP server isresponsible for which CMTS) and is aggregated in the mapping database849 (e.g., by DHCP configuration processing engine 853 running onaggregation server 851). The mapping database 849 is then exposed to therelay 843. The relay 843 reads from the map database 849. Engine 853running on server 851 automatically learns the DHCP servers serving eachCMTS by periodically pulling the configurations 835, 841, 842 out of theDHCP servers 807, 809, 810 and updating the mapping database (“relaymap”) 849. Initial population of database 849 and periodic updatesthereof are carried out in the same manner in one or more embodiments.In this regard, when engine 853 periodically pulls the configurations835, 841, 842 it compares them to the contents of database 849. Ifnothing is in database 849, engine 853 populates database 849 with thecontents of the config files. If there is data in database 849, engine853 compares the config files to the data present in database 849, andupdates same as needed. In one or more embodiments, in case of conflict,the oldest entry is used as described elsewhere herein. In someinstances, the periodic checking by engine 853 is triggered byre-loading of the DHCP server software. In an alternative embodiment,engine 853 could simply re-write the data in database 849 upon such are-load, without comparison and conflict checking.

As noted above, some embodiments have any one, some, or all of thefollowing optional features. DHCP packets include various kinds ofinformation; for example:

-   -   IP address of the CMTS,    -   type of device 813, 815, 817, 819 (e.g., a WINDOWS PC, DOCSIS        cable modem, PacketCable Multimedia terminal adapter (MTA);        DOCSIS cable modems include the make and model of the device),    -   what version of DOCSIS the device 813, 815, 817, 819 supports        (DOCSIS cable modems typically include this information),    -   for a cable modem, e.g., the make and model and what software        version is running.

Therefore, the relay 843 could select the destination based on more thanjust the source of the lease request or other DHCP message (i.e., whichCMTS the lease request or other DHCP message originated from). Instead,the relay could, for example, send all DOCSIS 3.0 lease requests orother DHCP messages to a certain DHCP server, in a different group thanother DHCP servers.

Thus, the relay 843 can use any information in the DHCP request packetto choose a back-end DHCP server; this decision need not be based inwhole or part on the identity of the originating CMTS. That is to say,the decision could be based solely on the identity of the originatingCMTS; on the identity of the originating CMTS and other information inthe DHCP request, or on other information in the DHCP request withoutregard to the identity of the originating CMTS.

In some cases, the relay 843 re-writes the DHCP packets. For example,suppose a CMTS sends out an incorrect value for one of the options. Whenthe relay forwards the packet to the DHCP server, the DHCP server is“unhappy” because the information in the packet does not match. Toaddress this scenario, in some instances, the relay rewrites thatparticular option in the DHCP request to make the DHCP server accept therequest. Thus, in some embodiments, the relay has the capability torewrite or “fix” DHCP options within the DHCP message to “please” theDHCP server, or to address any peculiar implementations on the client orthe relay agent (which is the CMTS).

In one or more embodiments, relay 843 is used for both DHCP v.4 and DHCPv.6. This is useful in a variety of contexts; especially in theaforementioned case when an MSO relocates DHCP servers to one or morenational data centers. Such activities may take place while a transitionto IPv6/DHCP v.6 is underway. When employing a relay 843 in accordancewith one or more aspects of the invention in such cases, making therelay functional with both DHCP v.4 and DHCP v.6 essentially eliminatesthe need to carry out any configuration on CMTSs again. Advantageously,once a solution in accordance with one or more embodiments is deployed,an operations team is free to move CMTSs between DHCP servers atleisure, without having to actually touch the CMTSs.

Note that FIG. 8 only shows three DHCP servers 807, 809, and 810;however, more are suggested by the ellipsis. Suppose there are on theorder of one hundred DHCP servers behind the relay 843 and they are allcomparatively idle (i.e., underutilized). An operations team cancollapse the one hundred servers into fifty servers, for example. A DHCPserver that before had ten CMTSs on it now has twenty. Assume, forexample, that all necessary work is done to orchestrate moving the CMTSconfiguration from the old DHCP server to the new one, and to move allof the DHCP lease information, and so on. If all of this is accomplishedduring the maintenance window and the DHCP server is correctlyconfigured, the CMTS does not need to change or even be aware that thework has taken place and that one hundred DHCP servers have beenreplaced by fifty DHCP servers, since the CMTS talks only to DHCP relay843. This aspect provides an operations team with greater flexibilityfor, e.g., load balancing and other operational requirements, withoutthe need to coordinate with a regional network engineer who wouldotherwise have to log into each of the CMTSs that are being impacted atthe exact time the DHCP change is being made and reconfigure each of theCMTSs. One or more embodiments advantageously simplify the operationalaspect of DHCP management because they decouple the DHCP server topologyfrom the CMTS.

As noted, in some embodiments, map data 849 is extracted from the DHCPservers. In one or more embodiments, there is a software component(daemon) 831, 837, 838 running on each of the DHCP servers, which daemondetects that the DHCP server has been reloaded. An individual DHCPserver has to be reloaded to apply any configuration changes. The daemon831, 837, 838 runs on each DHCP server and detects when the DHCP serverhas been reloaded, which generally implies a configuration change.Whenever the DHCP server has been reloaded, its configuration isextracted by daemon 831, 837, 838 using one or more APIs 833, 839, 840provided by the vendor. The daemon 831, 837, 838 obtains theconfiguration file 835, 841, 842 and transfers it up to aggregationserver 851 which collects all the configurations for all the DHCPservers in a particular location. The aggregation server processes allthe configuration files 835, 841, 842 and builds the aggregate map data849.

Aggregation server 851 may or may not be on the same physical server asDHCP relay 843. Aggregation server 851 takes DHCP configurations 835,841, 842; identifies the network blocks/IP blocks, and builds the map849.

Consider a case where DHCP server DHCP₁ and DHCP server DHCP₂ haveconfigurations that conflict. For example, suppose they are bothconfigured to serve the same network ranges for the same CMTS. In someembodiments, in case of duplicates, relay 843 uses the oldest matchfirst. Aggregation server 851, when it extracts the information, appliesmarking or time stamping, i.e., “this is the first time I have seen thisIP block on this DHCP server.” If, later on, another DHCP server comesup and states that it is also responsible for that block, one or moreembodiments default to the original server that the given address spacewas seen on, and send an exception to flag for human intervention toresolve the discrepancy. One or more embodiments default to the olderDHCP server because that is the one most likely to have been working atone point. In general, DHCP servers may be managed by different groupsof people. One or more embodiments seek to provide a safeguard such thatif one person types in the wrong information, it will not break DHCPconnectivity for some other region or CMTS. Therefore, one or moreembodiments adopt the approach of defaulting to using the oldestinformation in case of a conflict.

Thus, in one or more embodiments, a daemon 831, 837, 838 on each DHCPserver 807, 809, 810 uploads changes to aggregation server 851.

Note that DHCP relay 843 is shown as a single relay device in FIG. 8.Some embodiments take a simple approach and employ only a single relaydevice for each group of DHCP servers. However, in some instances, asseen in FIG. 9, a more sophisticated approach is provided, wherein thereare several relay servers behind a load balancer (different physicalservers or different virtual servers running on one or more physicalmachines). As seen in FIG. 9, a more sophisticated form of DHCP relay901 includes DHCP relay servers 1 to n, numbered 903, 905, 907, withload balancer 909 to balance the load among the servers. It should benoted that the skilled artisan, given FIGS. 8-9, accompanying text, andother teachings herein, will be able to balance the DHCP relay loadamong multiple instances of the DHCP relay.

In FIG. 8, CMTS_(A) has IP address 24.1.1.1, and CMTS_(B) has IP address24.2.2.2. DHCP relay 843 has IP address 1.2.3.1. Referring bask to FIG.7, in the current approach depicted therein, over each CMTS is the“helper” IP address, i.e., 1.2.3.4 for CMTS_(A) and 1.2.3.5 for CMTS_(B)(in each case, the actual IP address of the DHCP server 707, 709). Inthe exemplary embodiment of FIG. 8, each CMTS 801, 803 has the helperaddress equal to the relay IP address, namely, 1.2.3.1. DHCP₁ 807 withaddress 1.2.3.4 supports CMTS_(A) 801. DHCP₂ 809 with address 1.2.3.5supports CMTS_(B) 803. Relay 843 relays lease requests or other DHCPmessages to the appropriate DHCP server. Advantageously, in a modernnetwork operated by an MSO, where there may be on the order of twothousand CMTSs, each CMTS will point to the same two IP addressesbecause of the two national data centers (i.e., each CMTS points to theIP address of the relay 843 (or load balancer if used) in one of the twoNDCs and to the IP address of the relay 843 (or load balancer if used)in the other of the two NDCs). In one or more embodiments, the CMTSs donot have a concept of primary and secondary or back-up as regards theservers; the servers themselves determine which is primary or secondaryor back-up. For example, in FIG. 8, CMTS_(A) has the address of therelay 1.2.3.1 as one helper address, and the address of the relay inanother national data center as the other helper address; the relaysand/or servers in the national data centers are programmed to determinewhich is primary and which is secondary or back-up. In some cases, theprimary site is chosen based on physical proximity to the CMTSs itsupports. In other embodiments, one data center is entirely primary andanother is entirely secondary or back-up.

As noted, one or more embodiments are useful in a variety of contextsbesides a cable network. However, in the non-limiting example of FIG. 8,the CMTSs 801, 803 can be located in head ends 150 and the DHCP serversare located in one or more national data centers 1049. Thiscentralization of the DHCP servers facilitates the use of the relay,which is located in the national data center(s) 1049, logically in frontof the DHCP servers 807, 809, 810. Some DHCP products employ an activeDHCP server and a standby DHCP server. In some embodiments, the activeDHCP server is in one NDC and the standby DHCP server is in a differentNDC. There is a relay 843 in front of each group of DHCP servers. Thetwo helper addresses that point to the relay cover the active andback-up data centers.

In FIG. 8, the dashed lines labeled “DHCP Request” represent DHCP leaserequests or other DHCP messages from CMTS_(A) 801 to DHCP₁ 807 and fromCMTS_(B) 803 to DHCP₂ 809; in each case, the request is directed toRelay 843 which routes it in accordance with the map data 849. Thedashed lines from the servers 807, 809 to the map data database 849represent the population and updating of the map data database 849 asdescribed in connection with the daemons, APIs, config files,aggregation server 851, and engine 853. Any suitable configuration canbe employed for network 805; in some cases, the interconnections shownin FIG. 1 can be employed.

In some instances, aggregation server 851 also includes work assignmentengine 854. Engine 854 re-distributes CMTS-es from one DHCP server(e.g., 807) to another (e.g., 809). Engine 854 includes logic tore-distribute the CMTS-es across the population of DHCP servers 807,809, 810. In one or more embodiments, engine 854 will run periodicallyrather than continuously; for example, nightly. Engine 854, when makinga change, moves all the configuration information (e.g., from 835 to841) for the CMTS(es) that are being moved. Engine 854 also migrates thecorresponding DHCP lease information. Servers 807, 809, 810 keep trackof what addresses they have allocated, in a lease database—this is alsocarried over when making a change. By way of an example, suppose servers807 and 809 each initially had twenty assigned CMTS-es. Suppose server809 ended up being assigned to only ten CMTS-es due to changes in thenetwork. Engine 854 could re-assign five CMTS-es from server 807 toserver 809, so each would have fifteen.

Again, as noted, one or more embodiments are not limited to cablenetwork applications. One non-limiting example of an alternativeapplication is in a metropolitan Wi-Fi network. A metropolitan ormunicipal wireless network is the concept of turning an entire city intoa Wireless Access Zone, with the ultimate goal of making wireless accessto the Internet a universal service. This is usually done by providingmunicipal broadband via Wi-Fi to large parts or all of a municipal areaby deploying a wireless mesh network. The typical deployment design useshundreds of routers deployed outdoors, often on utility poles. Theoperator of the network acts as a wireless internet service provider.

For example, consider a situation where Wi-Fi access is provided at aplurality of access points all around a metropolitan area. The networkdevices that aggregate the network traffic from the Wi-Fi access pointsbehave in a similar manner to the CMTSs described in FIG. 8. They “see”the broadcast DHCP messages, and they are configured with a helperaddress. They forward the DHCP lease request messages or other DHCPmessages on to a DHCP server that knows how to handle them. Thus, theconcept of a DHCP relay 843 with a mapping database 849 can be used inconnection with any sort of network device that needs to be configuredwith a DHCP helper. The relay is placed between the DHCP servers and thenetwork device to mask the DHCP server topology. Thus, one or moreembodiments aggregate the DHCP servers using the relay for any kind ofnetwork architecture where there is a DHCP relay agent relaying DHCPmessages.

As noted, one or more embodiments provide a relay device 843 functionalwith both IPv4 and IPv6. In DHCP v.4, the relay 843 receives the requestand forwards it directly on to the DHCP server 807, 809, or 810. TheDHCP server responds directly to the CMTS; the relay does not have toroute the response. See the dotted lines in FIG. 8 labeled “IPv4”—inIPv6, the responses follow the reverse path back through the relay. Theresponse comes directly back from the DHCP server to the CMTS. In somecases, the relay 843 may have to re-write one of the options to get theDHCP server to accept the relayed message.

In DHCP v.6, per the protocol, relay messages and relay responses bothgo through the relay 843. Therefore, in DHCP v.6, the lease request will“hit” the relay 843. The relay 843 will encapsulate the lease request inanother form. There is, in DHCP v.6, a specific message type to make itclear to all the systems online how many times a message has beenrelayed. In DHCP v.6, the broadcast (more correctly, multicast in DHCPv.6) message is received by the CMTS; the CMTS wraps a so-called relayforward header onto the multicast message and forwards the multicastmessage on. The relay 843 receives the forwarded message, wraps anotherrelay forward header on the forwarded message, and relays the message tothe back-end DHCP server 807, 809, 810. The back-end DHCP serverprocesses the lease, makes all the decisions normally, and then respondsto the relay with a relay reply. The relay 843 strips off the headerthat it added and passes the message back to the CMTS. The CMTS stripsoff the header that it added and passes the message back to theconnected client 813, 815, 817, or 819. Thus, DHCP v.6 differs from DHCPv.4 in that there are specific messages in the protocol and the relayroutes both the requests and the responses.

As used herein, dynamic host configuration protocol (DHCP) without aqualifier is defined to include DHCP v.4 and DHCP v.6. DHCP v.4 isdefined in accordance with Internet Engineering Task Force (IETF) RFC2131, incorporated herein by reference in its entirety for all purposes,and DHCP v.6 is defined in accordance with IETF RFC 3315, incorporatedherein by reference in its entirety for all purposes.

The skilled artisan will appreciate that, in DHCPv4:

-   -   With respect to a DHCPDISCOVER packet: the client sends a        DHCPDISCOVER packet. In the IP section, the Destination address        is 255.255.255.255 (broadcast) and the Source address is        0.0.0.0. The DHCP section identifies the packet as a Discover        packet and identifies the client in two places using the        physical address of the network card. The values in the CHADDR        field and the DHCP: Client Identifier field are identical.    -   The broadcast DHCPDISCOVER packet is received by a Relay Agent        responsible for forwarding DHCP on the local network segment.        The Relay Agent inserts its IP address for the logical interface        on which it received the DHCPDISCOVER in the GIADDR field of the        DHCP header. The Relay Agent then forwards the packet using        unicast to the configured DHCP servers (known as DHCP helpers).        With respect to a DHCPOFFER packet: the DHCP server responds by        sending a DHCPOFFER packet. In the IP section, the Source        address is now the DHCP server IP address, and the Destination        address is the broadcast address 255.255.255.255. The DHCP        section identifies the packet as an Offer. The YIADDR field is        populated with the IP address the server is offering the client.        The CHADDR field still contains the physical address of the        requesting client. In the DHCP Option Field section, various        options are sent by the server along with the IP address; e.g.,        the Subnet Mask, Default Gateway (Router), Lease Time, and        Domain Name Servers.    -   The DHCP server sends the DHCPOFFER using unicast to the IP        address contained within the GIADDR field of the DHCPDISCOVER.        The DHCP Relay receives the packet and uses the GIADDR field to        determine on which directly connected interface to broadcast the        response. With respect to a DHCPREQUEST packet: the client        responds to the DHCPOFFER by sending a DHCPREQUEST. In the IP        section, the Source address of the client is still 0.0.0.0 and        the Destination for the packet is still 255.255.255.255. The        client retains 0.0.0.0 because the client hasn't received        verification from the server that it is acceptable to start        using the address offered. The Destination is still broadcast,        because more than one DHCP server may have responded and may be        holding a reservation for an Offer made to the client. This lets        those other DHCP servers know they can release their offered        addresses and return them to their available pools. The DHCP        section identifies the packet as a Request and verifies the        offered address using the DHCP: Requested Address field. The        DHCP: Server Identifier field shows the IP address of the DHCP        server offering the lease.    -   The broadcast DHCPREQUEST packet is received by a Relay Agent        responsible for forwarding DHCP on the local network segment.        The Relay Agent inserts its IP address for the logical interface        on which it received the DHCPREQUEST in the GIADDR field of the        DHCP header. The Relay Agent then forwards the packet using        unicast to the configured DHCP servers (known as DHCP helpers).        With respect to a DHCPACK packet: the DHCP server responds to        the DHCPREQUEST with a DHCPACK, thus completing the        initialization cycle. The Source address is the DHCP server IP        address, and the Destination address is still 255.255.255.255.        The YIADDR field contains the client's address, and the CHADDR        and DHCP: Client Identifier fields are the physical address of        the network card in the requesting client. The DHCP Option        section identifies the packet as an ACK.    -   The DHCP server sends the DHCPACK using unicast to the IP        address contained within the GIADDR field of the DHCPREQUEST.        The DHCP Relay receives the packet and uses the GIADDR field to        determine on which directly connected interface to broadcast the        response.

The skilled artisan will appreciate that, in DHCPv6:

-   -   a SOLICIT message is sent by a client to locate servers;    -   an ADVERTISE message is sent by a server in response to a        SOLICIT message to indicate availability;    -   a REQUEST message is sent by a client to request addresses or        configuration settings from a server;    -   a REPLY message is sent by a server to a client in response to a        SOLICIT, REQUEST, RENEW, REBIND, INFORMATION-REQUEST, CONFIRM,        RELEASE, or DECLINE message; and    -   a RECONFIGURE message is sent by a server to a client to        indicate that the server has new or updated configuration        settings.    -   A RELAY-FORW message is sent by a Relay Agent to relay messages        to other servers. The message being relayed is encapsulated        within a Relay Message option.    -   A RELAY-REPL message is sent by a server containing a response        message that a Relay Agent forwards to a client. The response        message is encapsulated within a Relay Message option.

An exemplary software architecture will now be discussed. One or moreembodiments include a daemon 831, 837, 838 on each DHCP server 807, 809,810. One or more embodiments also include map data database 849 withaggregation server 851, wherein a DHCP configuration processing engine853 runs on the aggregation server 851. When one of the DHCP servers807, 809, 810 uploads a new configuration, this engine awakes; it parsesthe configuration; it extracts all the pertinent data; and it comparesthis pertinent data against the data currently stored in the database849 to determine whether any address blocks have been added or removed,or if there are any duplicates.

The DHCP Relay 843 includes the actual relay software 847 as well as anagent 845 that periodically queries the map database 849. Note that theterms “agent” and “daemon” are more-or-less synonymous but to avoidconfusion, the pieces of software on the DHCP servers 807, 809, 810 arereferred to as daemons 831, 837, 838, while the piece of software on theDHCP relay 843 is referred to as agent 845. In one or more embodiments,rather than carrying out individual lookups against the map database,the whole database 849 is pushed onto the relay(s) 843 so that it ispresent locally. Agent 845 on the DHCP relay 843 synchronizes the mapdata by downloading updated maps. The map data from database 849 isperiodically persisted in a file on server 843 and the relay software847 periodically checks (e.g., once per second) for any changes in suchfile; the relay software 847 itself reloads the map data into memoryautomatically if it notices that the map has changed. By way ofclarification, in one or more embodiments, the map is memory residentfor speed; i.e., it is loaded into RAM on the machine(s) on which therelay(s) 843 execute.

In one or more embodiments, the relay instances 903, 905, 907 all actindependently as no state information needs to be shared.

Again, as noted and as depicted in FIG. 9, one or more embodimentsinclude a load balancer 909 in front of n relay servers 903, 905, 907.

In one or more embodiments, relays 843 are stateless because they do notneed to keep any state. All information necessary to route responses ispresent in the headers. More particularly, since DHCP v.4 responses donot need to be routed back through relay 843, there is no state.However, with regard to the DHCP v.6 messages that are going back andforth, they have enough information in the (relay forward) headers thatthe relays are stateless. The servers do not need to keep each otherapprised of what they are doing—they all act independently—effectivelyproviding a “clean” solution.

Thus, in one or more embodiments, map data is persisted in the mapdatabase 849 on, or accessible to, the aggregation server 851. The agent845 on the relay 843 uploads the data when there is a change, orperiodically checks it and uploads it, as discussed above. All the datais preferably maintained in RAM for speed. The DHCP relay thus includessoftware 847 that is kept loaded in RAM, and all the map data 849 isalso periodically updated and also kept loaded in RAM on whateverphysical server the DHCP relay runs on, for speed.

Some embodiments are employed in the context of a metropolitan Wi-Fi(“Metro Wi-Fi”) network, as seen in FIG. 11. In order to explain same,initially, consider again the HFC example, wherein both the cable modem(e.g., in CPE 106) and the devices communicating with same (e.g., PC232) receive a DHCP lease. In some instances, there is a wired and/orwireless router between the cable modem and the device(s). Thus, in theHFC environment, the cable modem and devices connected to it interactwith the DHCP server. Now, in the Metro Wi-Fi context, the DHCP comesdirectly from the device (e.g., lap-top computer or “smart”phone—omitted from FIG. 11) attached to the Wi-Fi network via wirelessaccess point 1344. The device attaches to the Wi-Fi network via accesspoint 1344, which bridges the traffic up controller/tunnel terminator1310, 1312) via a layer 2 tunnel. The controller/tunnel terminator 1310,1312 forwards the traffic to the layer 2 aggregator 1308.

In Metro Wi-Fi, there are multiple components which can function as DHCPrelay agents for connected devices. In some embodiments the PolicyEnforcer 1306 is employed as the DHCP relay, but the relaying functioncan be moved between the NAT (network address translation) router 1304and Policy Enforcer 1306. Router 1304 connects to Internet or backbone1302.

Metro Wi-Fi access points (APs) 1344 forward all their layer 2 trafficto a vendor specific concentrator. Some vendors have concentrators whichcan relay DHCP, and some vendors have access points that can relay DHCPnatively. The farther down the network the DHCP relaying is pushed, themore operationally complex it becomes to manage. If controllers orindividual APs act as DHCP relays, it is appropriate in one or moreembodiments to use the intermediary DHCP relay to abstract the actualbackend DHCP server infrastructure from the devices. A typical networkmay have tens of thousands of APs 1344 deployed. Having a consistentDHCP configuration across all the devices is a significant benefit.

Thus, in FIG. 11, remote relay devices analogous to relay functionalityon CMTS-es 801, 803 can be located, for example, at 1304, 1306, 1312,1344, or the like; the relays are not separately numbered in FIG. 11 toavoid clutter. Device(s) 1399 are analogous to devices 813, 815, 817,819 in FIG. 8. Block 1343 is analogous to DHCP intermediate relay 843 inFIG. 8. Behind block 1343 are elements analogous to elements 849, 851,853, 854, 807, 831, 833, 835, 809, 837, 839, 841, 810, 838, 840, 842 inFIG. 8, which function in an analogous manner, except that note would betaken of which Wi-Fi access points were assigned to which DHCP server,instead of which CMTS-es were assigned to which DHCP server. Furthermorein this regard, the last sentence assumes that the remote relays arelocated in Wi-Fi access points 1344; if they were located in terminators1310, 1312, note would be taken of which terminators were assigned towhich DHCP server; if they were located in enforcer(s) 1306, note wouldbe taken of which enforcer(s) were assigned to which DHCP server; and ifthey were located in NAT router(s) 1304, note would be taken of whichNAT router(s) were assigned to which DHCP servers.

Given the discussion thus far, it will be appreciated that, in generalterms, an exemplary method, according to an aspect of the invention,includes the step of obtaining, at an intermediary dynamic hostconfiguration protocol relay device such as 843 (or 901 with loadbalancer), 1343, over a network such as 805, 1302 plus intermediatecomponents (if any) in FIG. 11, a dynamic host configuration protocolmessage from one of a plurality of remote dynamic host configurationprotocol relay devices (e.g., CMTSs 801, 803 or remote relays in 1304,1306, 1312, or 1314) in communication with the intermediary dynamic hostconfiguration protocol relay device over the network. This step could becarried out, for example, by relay software 847 running on a server onwhich intermediate relay 843, 1343 resides.

With regard to messages obtained by device 843, 1343 in one or moreembodiments, UDP messages are employed. IP packets have a source anddestination IP address. The destination IP address is that of the loadbalancer 909 where employed, and the load balancer rewrites the packetto have a destination IP address for one of the DHCP relay servers 903,905, 907. If no balancer is used, the destination IP address is that ofthe relay device 843.

A further step includes accessing, by the intermediary dynamic hostconfiguration protocol relay device, data pertaining to a plurality ofdynamic host configuration protocol back-end servers (e.g., 807, 809,810) logically fronted by the intermediary dynamic host configurationprotocol relay device. This step could be carried out by software 847running on the aforementioned server, accessing map data in a RAM of theserver (the map data can be updated and loaded into RAM as describedelsewhere herein). A still further step includes, based on informationin the dynamic host configuration protocol message and the datapertaining to the plurality of dynamic host configuration protocolback-end servers, routing the dynamic host configuration protocolmessage to an appropriate one of the plurality of back-end dynamic hostconfiguration protocol servers. This step could also be carried out bysoftware 847 running on the aforementioned server.

In some cases, in the obtaining step, the remote dynamic hostconfiguration protocol relay devices are cable modem termination systems801, 803 and the network is a cable network (“pure” cable or HFC, forexample). However, other embodiments may involve different contexts. Forexample, in some cases, in the obtaining step, the network is amunicipal wireless network (e.g., Wi-Fi) and the remote dynamic hostconfiguration protocol relay devices each comprise remote dynamic hostconfiguration protocol relay devices located at one of a network addresstranslation router 1304, a policy enforcer 1306, a tunnel terminator1312, and a wireless access point 1344 of the municipal wirelessnetwork.

As an aside, it is worth noting that in FIG. 8, devices 813-819represent cable modems (with devices behind them).

In some cases, in the accessing step, the data pertaining to theplurality of dynamic host configuration protocol back-end servers is mapdata 849 that maps given ones of the plurality of remote dynamic hostconfiguration protocol relay devices 801, 803 to corresponding ones ofthe plurality of dynamic host configuration protocol back-end servers807, 809, 810. In the routing step, the pertinent information in thedynamic host configuration protocol message includes at least anidentifier of the remote dynamic host configuration protocol relaydevice in question.

Some embodiments further include updating the map data by receiving, atan aggregation server 851, an updated configuration file 835, 841, 842from at least one of the plurality of dynamic host configurationprotocol back-end servers 807, 809, 810; and updating the map data basedon the updated configuration file. These steps can be carried out usingthe daemons, APIs, and server 851 with engine 853, as describedelsewhere herein.

In some cases, in the routing step, the pertinent information in thedynamic host configuration protocol message further includes at leastone data item in addition to the identifier of the remote dynamic hostconfiguration protocol relay device in question. In some cases, in therouting step, the pertinent information in the dynamic hostconfiguration protocol message is information other than the identifierof the remote dynamic host configuration protocol relay device inquestion.

In some cases, additional steps include detecting at least one conflictin the map data 849 between at least two of the plurality of dynamichost configuration protocol back-end servers 807, 809, 810; andresolving the conflict by giving priority to the dynamic hostconfiguration protocol back-end server associated with the earliest timestamp. This step can be carried out, for example, by engine 853.

In some cases, both DHCPv4 and DHCPv6 can be handled. Thus, in somecases, in the obtaining and routing steps, the dynamic hostconfiguration protocol message is a lease request, such as a DHCPv4lease request, and the steps are repeated for a DHCPv6 lease request.Thus, in one or more embodiments, the dynamic host configurationprotocol lease request is a DHCPv4 DHCPREQUEST packet or a DHCPv6REQUEST message.

In some cases, the intermediary dynamic host configuration protocolrelay device 843 modifies the dynamic host configuration protocolmessage to affect how the appropriate one of the plurality of back-enddynamic host configuration protocol servers 807, 809, 810 processes themessage.

As noted, in a preferred but non-limiting approach, the relay 843 isimplemented as shown at 901 in FIG. 9. As also noted, in a preferred butnon-limiting approach, the relay software 847 and the map data are bothkept in RAM on the machine implementing relay 843, for speed.

In some cases, a further step includes periodically re-assigning atleast one of the plurality of dynamic host configuration protocolback-end servers 807, 809, 810 from one of the plurality of remotedynamic host configuration protocol relay devices to another one of theplurality of remote dynamic host configuration protocol relay devices;e.g., using work assignment engine 854 as described elsewhere herein.

In another aspect, an exemplary system includes an intermediary dynamichost configuration protocol relay device 843, 1343; a map database 849in communication with the intermediary dynamic host configurationprotocol relay device; and a plurality of dynamic host configurationprotocol back-end servers 807, 809, 810 logically fronted by theintermediary dynamic host configuration protocol relay device.Aggregation server 851 is included in some embodiments. Any of the otherelements in the figures can be included in some embodiments. Someembodiments include the components shown in FIG. 1; such embodiments mayhave a single NDC or two or more NDCs with redundancy.

System and Article of Manufacture Details

The invention can employ hardware aspects or a combination of hardwareand software aspects. Software includes but is not limited to firmware,resident software, microcode, etc. One or more embodiments of theinvention or elements thereof can be implemented in the form of anarticle of manufacture including a machine readable medium that containsone or more programs which when executed implement such step(s); that isto say, a computer program product including a tangible computerreadable recordable storage medium (or multiple such media) withcomputer usable program code configured to implement the method stepsindicated, when run on one or more processors. Furthermore, one or moreembodiments of the invention or elements thereof can be implemented inthe form of an apparatus including a memory and at least one processorthat is coupled to the memory and operative to perform, or facilitateperformance of, exemplary method steps.

Yet further, in another aspect, one or more embodiments of the inventionor elements thereof can be implemented in the form of means for carryingout one or more of the method steps described herein; the means caninclude (i) specialized hardware module(s), (ii) software module(s)executing on one or more general purpose or specialized hardwareprocessors, or (iii) a combination of (i) and (ii); any of (i)-(iii)implement the specific techniques set forth herein, and the softwaremodules are stored in a tangible computer-readable recordable storagemedium (or multiple such media). Appropriate interconnections via bus,network, and the like can also be included.

FIG. 10 is a block diagram of a system 1200 that can implement at leastsome aspects of the invention, and is representative, for example, ofDHCP relay 843, 1343 and/or one or more of the servers shown in thefigures. As shown in FIG. 10, memory 1230 configures the processor 1220to implement one or more methods, steps, and functions (collectively,shown as process 1280 in FIG. 10). The memory 1230 could be distributedor local and the processor 1220 could be distributed or singular.Different steps could be carried out by different processors.

The memory 1230 could be implemented as an electrical, magnetic oroptical memory, or any combination of these or other types of storagedevices. It should be noted that if distributed processors are employed,each distributed processor that makes up processor 1220 generallycontains its own addressable memory space. It should also be noted thatsome or all of computer system 1200 can be incorporated into anapplication-specific or general-use integrated circuit. For example, oneor more method steps could be implemented in hardware in an ASIC ratherthan using firmware. Display 1240 is representative of a variety ofpossible input/output devices (e.g., keyboards, mice, and the like).Every processor may not have a display, keyboard, mouse or the likeassociated with it.

As is known in the art, part or all of one or more aspects of themethods and apparatus discussed herein may be distributed as an articleof manufacture that itself includes a tangible computer readablerecordable storage medium having computer readable code means embodiedthereon. The computer readable program code means is operable, inconjunction with a computer system (including, for example, system 1200or processing capability on intermediate relay 843, 1343, or the like),to carry out all or some of the steps to perform the methods or createthe apparatuses discussed herein. A computer readable medium may, ingeneral, be a recordable medium (e.g., floppy disks, hard drives,compact disks, EEPROMs, or memory cards) or may be a transmission medium(e.g., a network including fiber-optics, the world-wide web, cables, ora wireless channel using time-division multiple access, code-divisionmultiple access, or other radio-frequency channel). Any medium known ordeveloped that can store information suitable for use with a computersystem may be used. The computer-readable code means is any mechanismfor allowing a computer to read instructions and data, such as magneticvariations on a magnetic media or height variations on the surface of acompact disk. The medium can be distributed on multiple physical devices(or over multiple networks). As used herein, a tangiblecomputer-readable recordable storage medium is defined to encompass arecordable medium, examples of which are set forth above, but is definednot to encompass a transmission medium or disembodied signal.

The computer systems and servers and other pertinent elements describedherein each typically contain a memory that will configure associatedprocessors to implement the methods, steps, and functions disclosedherein. The memories could be distributed or local and the processorscould be distributed or singular. The memories could be implemented asan electrical, magnetic or optical memory, or any combination of theseor other types of storage devices. Moreover, the term “memory” should beconstrued broadly enough to encompass any information able to be readfrom or written to an address in the addressable space accessed by anassociated processor. With this definition, information on a network isstill within a memory because the associated processor can retrieve theinformation from the network.

Accordingly, it will be appreciated that one or more embodiments of thepresent invention can include a computer program comprising computerprogram code means adapted to perform one or all of the steps of anymethods or claims set forth herein when such program is run, forexample, on a server implementing one or more of blocks/sub-blocks 843,851, 807, 809, 810, 845, 847, 853, 831, 833, 835, 837, 839, 841, 838,840, 842, 854 or analogous elements in other embodiments such as theMetro Wi-Fi embodiment of FIG. 11, and the like, and that such programmay be embodied on a tangible computer readable recordable storagemedium. As used herein, including the claims, unless it is unambiguouslyapparent from the context that only server software is being referredto, a “server” includes a physical data processing system (for example,system 800 as shown in FIG. 8) running a server program. It will beunderstood that such a physical server may or may not include a display,keyboard, or other input/output components. Furthermore, as used herein,including the claims, a “router” includes a networking device with bothsoftware and hardware tailored to the tasks of routing and forwardinginformation.

Furthermore, it should be noted that any of the methods described hereincan include an additional step of providing a system comprising distinctsoftware modules embodied on one or more tangible computer readablestorage media. All the modules (or any subset thereof) can be on thesame medium, or each can be on a different medium, for example. Themodules can include any or all of the components shown in the figures(e.g. modules/sub-modules to implement blocks/sub-blocks 843, 851, 807,809, 810, 845, 847, 853, 831, 833, 835, 837, 839, 841, 838, 840, 842,854 or analogous elements in other embodiments such as the Metro Wi-Fiembodiment of FIG. 11). The method steps can then be carried out usingthe distinct software modules of the system, as described above,executing on one or more hardware processors. Further, a computerprogram product can include a tangible computer-readable recordablestorage medium with code adapted to be executed to carry out one or moremethod steps described herein, including the provision of the systemwith the distinct software modules.

Accordingly, it will be appreciated that one or more embodiments of theinvention can include a computer program including computer program codemeans adapted to perform one or all of the steps of any methods orclaims set forth herein when such program is implemented on a processor,and that such program may be embodied on a tangible computer readablerecordable storage medium. Further, one or more embodiments of thepresent invention can include a processor including code adapted tocause the processor to carry out one or more steps of methods or claimsset forth herein, together with one or more apparatus elements orfeatures as depicted and described herein.

Although illustrative embodiments of the present invention have beendescribed herein with reference to the accompanying drawings, it is tobe understood that the invention is not limited to those preciseembodiments, and that various other changes and modifications may bemade by one skilled in the art without departing from the scope orspirit of the invention.

What is claimed is:
 1. A method comprising the steps of: obtaining, atan intermediary dynamic host configuration protocol relay device, over anetwork, a dynamic host configuration protocol message from one of aplurality of remote dynamic host configuration protocol relay devices incommunication with said intermediary dynamic host configuration protocolrelay device over said network; accessing, by said intermediary dynamichost configuration protocol relay device, data pertaining to a pluralityof dynamic host configuration protocol back-end servers logicallyfronted by said intermediary dynamic host configuration protocol relaydevice; and based on information in said dynamic host configurationprotocol message and said data pertaining to said plurality of dynamichost configuration protocol back-end servers, routing said dynamic hostconfiguration protocol message to an appropriate one of said pluralityof back-end dynamic host configuration protocol servers.
 2. The methodof claim 1, wherein, in said obtaining step, said remote dynamic hostconfiguration protocol relay devices comprise cable modem terminationsystems and said network comprises a cable network.
 3. The method ofclaim 1, wherein, in said obtaining step, said network comprises amunicipal wireless network and said remote dynamic host configurationprotocol relay devices each comprise remote dynamic host configurationprotocol relay devices located at one of a network address translationrouter, a policy enforcer, a tunnel terminator, and a wireless accesspoint of said municipal wireless network.
 4. The method of claim 1,wherein: in said accessing step, said data pertaining to said pluralityof dynamic host configuration protocol back-end servers comprises mapdata that maps given ones of said plurality of remote dynamic hostconfiguration protocol relay devices to corresponding ones of saidplurality of dynamic host configuration protocol back-end servers; andin said routing step, said information in said dynamic hostconfiguration protocol message comprises an identifier of said one ofsaid plurality of remote dynamic host configuration protocol relaydevices.
 5. The method of claim 4, further comprising updating said mapdata by: receiving, at an aggregation server, an updated configurationfile from at least one of said plurality of dynamic host configurationprotocol back-end servers; and updating said map data based on saidupdated configuration file.
 6. The method of claim 4, wherein, in saidrouting step, said information in said dynamic host configurationprotocol message further comprises at least one data item in addition tosaid identifier of said one of said plurality of remote dynamic hostconfiguration protocol relay devices.
 7. The method of claim 4, furthercomprising: detecting at least one conflict in said map data between atleast two of said plurality of dynamic host configuration protocolback-end servers; and resolving said conflict by giving priority to oneof said at least two of said plurality of dynamic host configurationprotocol back-end servers associated with an earliest time stamp.
 8. Themethod of claim 1, wherein, in said routing step, said information insaid dynamic host configuration protocol message comprises informationother than an identifier of said one of said plurality of remote dynamichost configuration protocol relay devices.
 9. The method of claim 1,wherein, in said obtaining and routing steps, said dynamic hostconfiguration protocol message comprises a DHCPv4 lease request, furthercomprising: obtaining, at said intermediary dynamic host configurationprotocol relay device, over a network, a DHCPv6 lease request fromanother one of said plurality of remote dynamic host configurationprotocol relay devices; accessing, by said intermediary dynamic hostconfiguration protocol relay device, said data pertaining to saidplurality of dynamic host configuration protocol back-end serverslogically fronted by said intermediary dynamic host configurationprotocol relay device; and based on information in said DHCPv6 leaserequest and said data pertaining to said plurality of dynamic hostconfiguration protocol back-end servers, routing said DHCPv6 leaserequest to another appropriate one of said plurality of back-end dynamichost configuration protocol servers.
 10. The method of claim 1, furthercomprising said intermediary dynamic host configuration protocol relaydevice modifying said dynamic host configuration protocol message toaffect how said appropriate one of said plurality of back-end dynamichost configuration protocol servers processes said dynamic hostconfiguration protocol message.
 11. The method of claim 1, furthercomprising periodically re-assigning at least one of said plurality ofdynamic host configuration protocol back-end servers from one of saidplurality of remote dynamic host configuration protocol relay devices toanother one of said plurality of remote dynamic host configurationprotocol relay devices.
 12. An intermediary dynamic host configurationprotocol relay device comprising: a memory; and at least one processor,coupled to said memory and operative to: obtain, over a network, adynamic host configuration protocol message from one of a plurality ofremote dynamic host configuration protocol relay devices incommunication with said intermediary dynamic host configuration protocolrelay device over said network; accessing data pertaining to a pluralityof dynamic host configuration protocol back-end servers logicallyfronted by said intermediary dynamic host configuration protocol relaydevice; and based on information in said dynamic host configurationprotocol message and said data pertaining to said plurality of dynamichost configuration protocol back-end servers, route said dynamic hostconfiguration protocol message to an appropriate one of said pluralityof back-end dynamic host configuration protocol servers.
 13. Theintermediary dynamic host configuration protocol relay device of claim12, wherein: said data pertaining to said plurality of dynamic hostconfiguration protocol back-end servers comprises map data that mapsgiven ones of said plurality of remote dynamic host configurationprotocol relay devices to corresponding ones of said plurality ofdynamic host configuration protocol back-end servers; and saidinformation in said dynamic host configuration protocol messagecomprises an identifier of said one of said plurality of remote dynamichost configuration protocol relay devices.
 14. The intermediary dynamichost configuration protocol relay device of claim 13, wherein saidinformation in said dynamic host configuration protocol message furthercomprises at least one data item in addition to said identifier of saidone of said plurality of remote dynamic host configuration protocolrelay devices.
 15. The intermediary dynamic host configuration protocolrelay device of claim 12, wherein said information in said dynamic hostconfiguration protocol message comprises information other than anidentifier of said one of said plurality of remote dynamic hostconfiguration protocol relay devices.
 16. The intermediary dynamic hostconfiguration protocol relay device of claim 12, wherein said dynamichost configuration protocol message comprises a DHCPv4 lease request,and wherein said at least one processor is further operative to: obtaina DHCPv6 lease request from another one of said plurality of remotedynamic host configuration protocol relay devices; access said datapertaining to said plurality of dynamic host configuration protocolback-end servers logically fronted by said intermediary dynamic hostconfiguration protocol relay device; and based on information in saidDHCPv6 lease request and said data pertaining to said plurality ofdynamic host configuration protocol back-end servers, route said DHCPv6lease request to another appropriate one of said plurality of back-enddynamic host configuration protocol servers.
 17. The intermediarydynamic host configuration protocol relay device of claim 12, whereinsaid at least one processor is further operative to modify said dynamichost configuration protocol message to affect how said appropriate oneof said plurality of back-end dynamic host configuration protocolservers processes said dynamic host configuration protocol message. 18.An apparatus comprising: means for obtaining, at an intermediary dynamichost configuration protocol relay device, over a network, a dynamic hostconfiguration protocol message from one of a plurality of remote dynamichost configuration protocol relay devices in communication with saidintermediary dynamic host configuration protocol relay device over saidnetwork; means for accessing, by said intermediary dynamic hostconfiguration protocol relay device, data pertaining to a plurality ofdynamic host configuration protocol back-end servers logically frontedby said intermediary dynamic host configuration protocol relay device;and means for, based on information in said dynamic host configurationprotocol message and said data pertaining to said plurality of dynamichost configuration protocol back-end servers, routing said dynamic hostconfiguration protocol message to an appropriate one of said pluralityof back-end dynamic host configuration protocol servers.
 19. A systemcomprising: an intermediary dynamic host configuration protocol relaydevice; a map database in communication with said intermediary dynamichost configuration protocol relay device; and a plurality of dynamichost configuration protocol back-end servers logically fronted by saidintermediary dynamic host configuration protocol relay device; wherein:said intermediary dynamic host configuration protocol relay device isconfigured to obtain, over a network, a dynamic host configurationprotocol message from one of a plurality of remote dynamic hostconfiguration protocol relay devices in communication with saidintermediary dynamic host configuration protocol relay device over saidnetwork; said intermediary dynamic host configuration protocol relaydevice is configured to access said map database, said map databasecontaining data pertaining to said plurality of dynamic hostconfiguration protocol back-end servers logically fronted by saidintermediary dynamic host configuration protocol relay device; and saidintermediary dynamic host configuration protocol relay device isconfigured to, based on information in said dynamic host configurationprotocol message and said data pertaining to said plurality of dynamichost configuration protocol back-end servers, route said dynamic hostconfiguration protocol message to an appropriate one of said pluralityof back-end dynamic host configuration protocol servers.
 20. The systemof claim 19, wherein: said data pertaining to said plurality of dynamichost configuration protocol back-end servers comprises map data thatmaps given ones of said plurality of remote dynamic host configurationprotocol relay devices to corresponding ones of said plurality ofdynamic host configuration protocol back-end servers; and saidinformation in said dynamic host configuration protocol messagecomprises an identifier of said one of said plurality of remote dynamichost configuration protocol relay devices; further comprising anaggregation server in communication with said map database and saidplurality of dynamic host configuration protocol back-end servers, whichreceives an updated configuration file from at least one of saidplurality of dynamic host configuration protocol back-end servers, andwhich updates said map data based on said updated configuration file.21. The system of claim 20, wherein said aggregation server isconfigured to periodically re-assign at least one of said plurality ofdynamic host configuration protocol back-end servers from one of saidplurality of remote dynamic host configuration protocol relay devices toanother one of said plurality of remote dynamic host configurationprotocol relay devices.